Dulles Tier 2/Concourse C Connector

State-of-the-Art Intra-Airport Transportation

Due to Clark's commitment to schedule, cost and quality, Clark completed and opened the challenging project ahead of schedule as requested by the Authority. Most importantly, Clark had an exceptional safety record, working twenty-three months and completing the job with zero lost-time accidents and zero recordable accidents. This project was the Airport Authority's Safety Award Winner for the year 2009, demonstrating excellent safety practices and keeping safety a priority at all times with a perfect safety record.

In 2000, the Metropolitan Washington Airports Authority (MWAA) initiated the D2 – Dulles Development program to accommodate increased growth and improve the traveler’s experience. An essential component of the capital improvement program was the installation of the Dulles AeroTrain, a new $2 billion APM system that connects the various gates and terminals. The construction of the APM was broken into several phases, and Tier 2 was the last contract to be procured that completed the system.

The cast-in-place concrete pedestrian tunnel is 40 feet wide and 450 feet long and crosses under an active aircraft taxiway. The Clark team performed a 30,000 cubic yards of soil and rock excavation that was 30 feet deep.

Excavation included supporting an existing 54-inch diameter, reinforced-concrete storm-water pipe, and the design also took into account the additional loads of the adjacent aircrafts. The tunnel required 6,800 cubic yards of concrete and 630 tons of rebar.

The tunnel contains two 250-foot-long moving walkways, and the walls follow a unique hexagonal shape. To achieve the desired effect, the concrete work required custom forms. Work in the tunnel also included relocating existing underground utilities, including a 12-inch-diameter jet-fuel pipe.

Clark had to maintain service vehicle traffic across the excavation. A temporary bridge was designed and constructed by Clark to serve as this roadway.

Passengers using the tunnels enter Concourse C through the new vertical circulation building. The building’s exterior consists of metal wall and roof panels and a section of single-ply membrane roofing. Four escalators and two three-story hydraulic elevators carry passengers the 38 vertical feet between the concourse level and the tunnel.

The finished ceiling is 35 feet above the finished floor and continues on a slope above the four escalators. In order to meet the schedule, construction on the escalators occurred simultaneously with the ceiling work above on an engineered scaffold. The scaffold system to install the ceiling was erected after the escalators were set in place.

Dulles remained fully operational throughout the project. Clark designed innovative and cost-efficient support of excavation systems, executed the complicated work ahead of schedule, as requested by the owner, and, despite the added obstacle of working adjacent to an active taxiway, held a perfect safety record. The high standard brought to the Tier 2 project by the team not only met but exceeded the owner’s expectations and allowed for the successful opening of the APM system.